Composition of the PKR variant library.
(A) Barchart depicts the number of variants made at each of the four PKR windows categorized by amino acid properties: Positive Charge = H, K, R; Negative Charge = D, E; Polar-Neutral = C, N, Q, S, T; Non-Polar = A, I, L, M, V; Aromatic = F, W, Y; Unique = G, P; Stop = *. A total of 140 variants were made in α0/β1, 86 in αD, 43 in the Activation Loop, and 161 in αG for a total of 430 variants, which includes the 4 nonsense variants made in each window. (B) Histogram depicts the number of unique barcodes linked to each PKR variant, with a mean of 42.83.